Method of making articles from organic dispersions



Oct. 20, 19551. G. w. TROBRIDGE ET AL 1,828,481

METHOD OF MAKING ARTICLES FROM ORGANIC DISRERSIONS Filed May 2e, 1930mama oef. zo, 1931 UNITED sra'rasA PATE-Nr oPFlc/E- anonym monmnen, 'orlsurvivor: commu, EDWARD ARTHUR or nnDnre'roN, nrmmvenm, DoUeLns mm:mss. on mm: GREEN, WALTER. emanen sonnen, or minoren, :emu-menu.ENGLAND, assumons 'ro DUNLOP numana conm LmrrnD, or Drnumenm, ENGLAND, nBRITISH centraux 'mon or Inma armonas rama 03eme DIsrnasIoNs applicationmea lay as, 1930, serial 110.455.694, and in Great Braam ln'y as; 192e.

Our resent invention relates to a method of ma 'ng sponge articlesdirectly from aqueous dispersions of organic materials, and

A particularly rubber and rubber like materials. i When a mass 'ofunvulcanzed sponge material has been formed, the particles of airentrapped or enclosed inthe sponge act as a heat msulator and,therefore, prevent or impede the penetration of the heat of vulcanizal0,tion into theinterior of the mass and thus revent a uniform heat andvulcanization. Iponge rubber articles of considerable size such ascushions, mattresses, etc., have, therefore, usually been assembled fromsubstan- ,ll tially laminar units of such limited thickness as to rmitadequate transfer of heat from the si es of the unitsf An object of theresent invention'is to provide a method an apparatus whereby an 80article or mass f sponge rubber of any desired size may gral unitarymass.

Another object of the invention is to pro- 4, vide a mold having heatingelements pro] ect- 25, ing into the interior of themold and of suchcross section that they may be withdrawn without displacing any of theinterior vol'- ume of said mold. With these and other objects in viewwhich will more fully appear from the following description, thelinvention comprises the method of treatment and the mold described inthe following specification. The various features of the invention areillustil'ted in the accompanying drawings,

in whichv Fig. 1 is a perspective view of a mold'embodying a preferredform of the invention. the top 'or upper `side of the mold being removedto show the interior.

Fig. 2 is a plan view of the mold shown in Fig. 1, with the top removed,and

Fig. 3 is an elevation of the mold.

In our invention aqueous dispersions of 5 rubber umaterials areintroduced into the molds preferably of internal dimensionssubstantially equal to the respective external dimensions of thearticles to beformed and provided with holes in which may be fitted Jdevices extending into or through the interior be made directly in aninteof the molds and of substantially uniform cross section, or of across section decreasing or varying in a uniform manner so thatit may bewithdrawn from the interior of the mold without distorting or dis lacingany of the rubber material centaine therein.

The molds may be of any suitable type and may be assembled from standardunits so as to be ofthe dimensionsv approximating those of the articlesit is desired to produce. The heating means for heating the interior ofthe mold may consist of any suitable heating means, as for example,electric heating means or .tubes open at one or both ends to receive theheating medium and transmit heat from the heating medium in which themold is immersed into the interior of the mold.

The emulsions or dispersions of rubber material to which the inventionmay be applied may consist! or comprise rubber, gutta percha, balata orsimilar vegetable resins occurrin naturally or obtained artificially, orof emu i sions or suspensions of artificial or synthetic resins or gums.Aqueous dispersions of co-l agulated rubber, of vulcanized .rubber,`synthetic rubber, waste or reclaimmay be em'- ployed as desired either asalternatives to or as admixtures in the rubber materials of theg` abovetype. The dispersions may contain the usual compounding andvulcanizing'ingredients. 'A concentrate of a rubber or latex prepared,for example, by stabilizing the latex with a colloid, such as a soap andarm monia, and then concentrated or evaporated with agitatiomasdescribed in application Serial No. 232,705 may be employed. Suchconcentrate may contain any one or more of the usual compoundingingredients, preferably excepting those which would tend to forminsoluble soaps or to increase the surface tension of the mixture. Theaqueous emulsions or dispersions may, if desired, be such as are, or canbe rendered, cap-able of gelling upon the application of heat or uponthe addition of substances to cause the emulsions or dispersions to gelin the cold after a definite and controllable time interval.

The sponge like structure may be produced in any known manner in thematerial subsequent to its solidification or, alternatively, m

msv

the emulsions or dispersions aforesaid can be first converted into afroth by means of a gas and the froth thereafter converted into aermanent spongy structure of lrreverslble so id material. 1

After the perforated sponge art1cle has gelled or set and, if desired,the coagulated material vulcanized, it may be removed from a plicationsSerial No. 232,705 and Serial o. 316,722 in which the latex is kept inconstant movement and concentrated without coyagulation:

Parts by weight Rubber 100 Sulphur 3 Zinc diethyldithiocarbamate 0.7Mineral oil 5.0 Caustic potash 0.4 Casein-; 0.1 w Oleic acid 0.5

The above ingredients are in the form of a latex cream sufficientlyviscous and concentrated to prevent the segregation of the compoundingingredients. 2 parts by weight of sodium silicofluoride based on the drymix- 49 ing areadded and the mass is then whipped q for a few minutes bywire mesh paddles or suitable stirrers or whipping machines, therebyconverting the mass into a frothy condition. 0.5 parts of zinc oxide arethen added asa dispersion, preferably being dispersed with casein. Thefroth thus obtained is then placed in a metal mold provided withheatpermitted to gel at normal atmospheric tem- 59 perature (16 3 C.) or(50 or 60 0.). The lgel- 'ling will occur in about 30 minutes. The moldis then placed in an autoclave and vulcanization carried out for onehour with steam at a pressure of five pounds. If hol- `low internalheating tubes are-employed, the access of steam to the interior of thetubes will heat and vulcanize the mass Within the mold substantiallyuniformly throughout. 60 The molded material may then be removed fromthe mold and dried by known means.

In the accompanying drawings a metallic mold 1 for vulcanizing a mass ofmaterial having dimensions of 16X16 5 is o5 shown.` The mold 1 isprovided with a rebottom of the mo ing elements of the type indicatedabove, and" The tubes 4 are movable lid or cover and with four rows ofsix vertical heating tubes 2, and with three rows of two horizontaltubes 3. All of the tubes 2 extend in arallel relation from top to d andare of uniform cross section so that the rubber article formed in themold may be removed lengthwise of these tubes without distortion. Theheating tubes 3 also extend in parallel relation from one end or side ofthe mold to the other and are of uniform cross section so that they maybe withdrawn through the mold without disturbing any part of thesurrounding molded material.

' The heating tubes 2 preferably consist of loose tubes fittingvertically over tubes fixed into`the bottom of the mold. The heatingtubes or devices 3 preferably consist of thin outertubes 5 substantiallyequal in le v h to the inside length of the mold and tting loosely overinner tubes 6. The tubes 3 project through the walls of the mold and areheld in position in the mold by means of cot'- ter pins 10 in therojecting parts adjacent the outer surface o the mold. The thin outertubes 5 of the heatin elements 3 may be made of metal and may iewithdrawn from the mold or, they may be of rubber and may remain in thearticle, the inner devices 3 only being withdrawn. The tubes 5 arefitted into the mold 1 prior to the insertion of the innerheating tubes6. The tubes 6 are open at both ends so that the heating material withinthe autoclave and surrounding the mold may enter the tubes 6 andcirculate therethrough to rapidly carry the heat into the interior ofthe mold. y

After the material within the mold has gelled and set and, if desired,has. been vul,- canized, the perforated sponge article thus produced isremoved from the mold without permanent distortion by removing thecotter pms 10 and sliding the tubes 6 out of the mold. The tubes 2, themain axes of which are substantially parallel to thel direction ofremoval of the article, may remain in the mold until after theremoval ofthe article, if desired. 7 v x The heating tubes 2 are illustrated asformed of loose vertical tubes 4 fixed into the bottom of the mold.provided with an open end 8 fitted into-the able steam orv other heatingiiuid to enter the tubes 2 and thus reach that part of the interior ofthe mold and of the material containedtherein and lying between the'heating tubes 5. When the mold 'is filled with material and prior toits insertion into'the auto-1 clave, the'open or top side is closed bymeans of a cover 11.

It will be understood that the dimensions of the mold may be increasedor decreased, as desired, and that the number or size of the bottomofthe mold 1 to enltubes fitting over -1.15

Y example, layers of woven fabric, may be provided Within the' materialin the mold and attached or. placed relative to said heating devices.vSuch supporting reinforcements may remain after vulcanization and mayserve as reinforcing components of the finished articles.

1. A method of making sponge articles in an integral mass whichcomprises molding a froth of a dispersion of rubber material to thedesired dimensions, heating said molded mass from the exterior, andconveying heat into the interior of said mass in -closely spacedparallel paths.

2. A method of making sponge articles in an integral mass whichcomprises molding a froth of a dispersion of rubber material to thedesired dimensions, heating said molded mass from the exterior, andconveying heat into the interior of said mass in closely spacedparallelA paths of uniform cross section.

3. A process of making sponge articles in an integral mass whichcomprises molding a froth of rubber material to the desired dimensions,surrounding said molded mass 8. The method of-claim 7 in which a Wovenfabric isused as a reinforcing means.

9. The method of making sponge articles in an integral mass whichcomprises molding a froth of a dispersionof rubber material to 7o thedesired dimensions and heating said froth interiorly in spaced channels.

In witness whereof we have hereunto setour hands. GEOFFREY WILLIAMTROBRIDGE. EDWARD ARTHUR MURPHY. DOUGLAS FRANK TWISS.

WALTER GEORGE GORHAM.

with a heating fluid, and conveying said heating fluid into the interiorof said mass in closely spaced parallel paths. v

4. A process of making sponge articles in an integral mass whichcomprises molding a froth of rubber material to thev desired dimensions,surrounding said molded mass with a heating fluid, and conveying saidheating 'fluid into the interior of said mass in closely spaced parallelpaths of uniform cross section. c

5. A process of forming integral molded masses of sponge structure whichcomprises forming a concentrated vulcanizable rubber material into afroth, forming said froth to .the required dimensions, enclosing saidmasses in a heating fluid at a vulcanizable temperature. and conveyingsaid heating fluid through said masses in closely spaced parallel paths.

6. A method of forming an integral mass i of sponge like structure whichcomprises forming a concentrated ,vulcanizable dispersion of rubbermaterial into aA froth, forming said froth to a mass of the requireddimensions, surrounding said mass with a heating fluid at a vulcanizingtemperature, and conveying said heating fluid through said mass inparallel paths, said paths being in two or more directions and ofsubstantially uniform cross section.

7. The method of claim 1 in which-a layer of reinforcement is embeddedin said mass prior to vulcanization.

